Combustion control in steam-boiler furnaces



Dec. 18,1928.

F. H. LINLEY COMBUSTION CONTROL IN STEAM BOILER FURNACES Filed Oct. 5, 1926 2 Sheets-Sheet l Dec. 18, 1928. 1,695,431 F. H. LINLEY v COMBUSTION CONTROL IN STEAM BOILER FURNACES Filed 001;. 5, 1926 2 Sheets-Sheet 2 Patented Dec. ,1s, 192si UNITED sir Ares PATENT OFFICE.

a ram) nrmnnr, or DULUTH, MINNESOTA. COMBUSTION CONTROL IN STEAMEQILER summons.

Application filed October 5, 1926. Serial No; 139,672.

My invention relates to improved means for controlling'combustion in furnaces and more particularly to a control means for maintaining a predetermined pressure in a combustion chamber by controlling the posi tion of a damper, the damper being opened provided with two electric circiiits, each connected to effect a rotation of the motor in one of the two directions and each containing a relay switch for connecting the motor through its particular circuit to a source of current. One or'the other of the relays is connected to a source of current for operation by a control switch which is movable according to pres sure conditions found in the combustion chamber, this last named switch comprising.

a movable contact point positioned between and spaced from two stationary contact points so that when the movable contact point is moved according to variances in pressure found in the combustion chamber, one

or the othercontact points is engaged to con** nect one or the other relays at the. extreme positions of movement of the movable contact point. a

One of the objects of my invention is to provide a means for automatically maintaining the pressure in a combustion chamber of a furnace substantially constant.

Another object of my invention is to ar.

vide a means for moving adamper used'in connection with a combustion chamberof. a

furnace in accordance with the existence of a certain pressure conditions in the combustion chamber.

Another ob]ect of my invention is to provide a means for opening a damper used in connection with a'combustion chamber of a furnace when the pressure in tlie'combustion chamber] reaches a certain predetermined maximum and for closingsaid damper-when a pressure in the combustion chamber decreases below a-certain predetermined-minimum.

able contact point, the movable contact point being positioned to engage one or the other of said fixed contact points at extreme positions of its movement, the movement of whieli is occasioned in accordance with the existence of varying conditions of pressure in the combustion chamber.

vide a motor having twocircuits of the type set-forth in the above stated object and. in

Another object of my invention is'to prowhich each circuit is provided with a limit switch adapted to be thrown to open position in a manner to stop the motor after the motor has been run a predetermined amount.

Another object of my invention is to pro-. vide a manually operable switch for controlling a motor connected in a system of the above describedtype so that the automatic. control means may be cut out and a manual switch may be employed for connecting one or the other of the motor circuits so as to cause an opening or closing of the damper as desired by the operator." 7 These and other objects are accomplished by meansof the arrangement disclosed on Figure 1 is a view of my control system I partly-in side elevation and partly diagrammatically represented. In this .figure the pressure responsive switch is disclosed showf ing the float and pipe connection leading to the combustion chamber, the remainingportion of the figure showing diagrammatically the electrical elements and connections;

Figure 2 is a plan view of the motor, remind-- Ition earing and screw. means forcontrollingthe amper and for automatically throwing the limit switches; and i Figure 3 is a side elevationof the arran ement disclosed in Figure 2, this figure is.-'

closing more full I thearrangement of the screw nut operating between the twoliinit switches.

The various novel features of the invention I relation the rod of insulating material 17. Mounted on the lower end of the rod 17 is a bell shaped float element 18 positioned in the receptacle 13 and over the upper end of the pipe 12 so that when the receptacle 13 is partially filled witha liquidsiich as oil to make a seal, the bell member 18 forms a float adapted to move up and down according to varying pressure conditions communicated to the interior of the bell 18 cross beam to one side of the center thereof is the insulating block 19 forming a support for the contact elements 20 and 21.

' Positioned between-the contact elements and mounted rigidlyon the rod 17 is a disk 22 adapted to form with the contact'elements 20 and 21 a double switch mechanism operating when the bell float is in extreme upward, ,position to connect one circuit of my system and when in extreme lower position to connect a second circuit of my system. The contact disk 22 is connected by the wire'23 having a resistance element 24 connected therein to one terminal of a source of current designated generally as A. Each of the other contact points 20 and 21 is connected by means of wires 25 and 26 respectively to a relay desig nated generally 27 and 28 and from thence by wire 29, switch 30, and wire 31 to the other terminal of the source of current designated generally as B.

An electrical motor adapted for rotation in either direction is designated generally as C and is provided'with a rotor 32 and'the split series coil 33 and 34, each connected in a separate circuit to terminalB of the source of current by relay switches 27 and 28. In each of the circuits just men tioned is a limit switch 35 and 36 adapted to cut oil the source of current in the particular circuit of each, the purpose and operation of which will be hereinafter described.

The first of the two circuits for connecting the motor for operation comprises the rotor 32 connected at one end of the terminal of the source of current A, coil 33, switch 35, wire 37, terminals 38 on the relay 27, wire 39, switch 30 and wire 31 completing the circuit. back to the terminal B of the source of current. The second circuit for connecting themotor comprises the rotor 32, coil 34, switch 36, wire 40, terminal 41 on the relay 28, wires 42 and 29, switch 30 and wire 31. Extendthrough pipes .1. 11 and 12. Mounted on the underside of the ing across these two circuits in a manner to cut out the relays of the automatic control mechanism are the two wires 43 and 44'l1aving the switch 45 connected intermediate their lengths in a manner to permit a connection of the motor through either one of the circuits selectively to thesource of current by amanual control so that the damper may be controlled independently of the automatic means. The switch 45 is provided with a movable switch arm 46 effective to connect either one of the circuits when the arm 47 of the switch 30 is contact 48.

Referring to Figures 2 and 3, the operating positioned to engage the means for the damper comprises a motor'designated through a coupling 49, a series of reduction gears housed in a casing 50 so as to rotate the shaft 60 extending out of the housing at a 90 angle to the axis of the motor. ,Positioned 'in the other end of the shaft 60 in a socket 61 is the finely threaded rod 62 heldin the socket by the pin 63 and having thread ed thereon a nut member 64. The outerend of the rod 62 is provided with sleeves 65 con nected by thepin 66 forming a connection for the second screw threaded shaft 67 held in the other end of the sleeve 65 by the pin 68. Mounted on this shaft, the threads of which are coarser than those on shaft 60, is the nut member 69 fixed in the outer end of the pipe 7 0 so as tomove the pipe longitudinally upon rotation of the shaft, thepipe 70 being connected to operate through suitable mechanical connections the damper of the combustion chamber. Depending from the nut 64 is an arm 71 positioned to slide in a groove 72 provided on the upper side of an electrical switch mechanism designated generally as 73. The switch 7 3 is provided with two pivots shown at 74 on which are mounted two contact arms 75 and 76 held normally by the spring 77 to engage the contact points 7 7 and 78 respectively. The upper ends of the arms are extended to a position to-be engaged by the lower end of-the depending arm 71 of the nut 64 insuch a manner that the nut 64 will engage onev or the other of'these arms at its extreme opposite positions of movement. The nut 64 issupplied with a grease cup 7 9, adapted to keep generally as C adapted to drive the threaded surface. between the nut and the a sually high pressure existing in the combustion chamber may be partially reduced by opening the damper employed. in connection. with the combustion chamber. Upon the exist'ence of such an extreme pressure, the bell float. member 18 is forced upwardly under the action of theincreasedpressure communicated to its interior to an extent causing the contact elements 22 ,to engage the contact point 20. When the parts are in this position, the

been set in operation as described will causerotation of the rod 62 and 67 as shown in Figures 2 and 3. 'The rotation of the rod 67 causes the nut 69 to move the pipe 70 in a manner to open the damper and at the same time the nut 64 'is forced to travel along the rod 62 so as to engage lthe switch arm 76,

' the switch arm 76 being that which is represented at 35 in Figure 1. From this arrangement it may be readily understood that after the float 18 has acted, through theinstrumentality of one or the other of the two relays to connect the motor for operation through one or the other or its circuits, the motor will run until contact is. broken between contacts 20 and 22. This breaking of contacts is caused by the lowering of the bell float member 18 due to the reduction of pressure in the combustion chamber-eifected .by

the closing of the damper. In case the dos-- 435 ing of the damper did not cause the necessary reduction of pressure, the motor would continue to run until the particular circuit connection efiectin the operation would be disconnected by t ,e moving arm 71 traveling.

40 along the rod 62,.thereby disengaging the pa'rticularswitc'h arm 7 5 or 76. From this explanation it. is apparent that when the pressure in the combustion chamber is diminished, a circuit is formed by the-contact points 22 and 21 .to operatethe relay 28 and switch arm 41 to establish a circuit to operate the'motor in the reverse direction,

the principle involved, however, in the above instances being the same. By movement of 5 the switch arm 47 of the switch 30 over to the point 48, the automatic control means may be entirely cut out and the motor operatedin a direction to either open the damper or to close the damper at the will of the operator merely. by manipulating the control switch designated generally 25.

Iclaimr, I 1. In combustion control mechanism, means for operating a damper comprising a 0 motor having two circuits, one for each di-'- rection of rotation,-each circuit being adapted to be connected to a source of current by a relay, means for operating one. or the other of said relays depending upon pressure con- 5 ditions in a combustion chamber, comprising a double switch mechanism having two fixed contact points and a movable contact oint, the movable contact point and one 0 said two contact points being connected when the pressure in said combustion chamber increases a certain predetermined extent and the movable contact point and the other of said two contact points being connected when said pressure in said combustion chamber diminishes to a certain predetermined extent.

2. In combustion control mechanism, a reversible motor for opening and closing a damper, means for operating said motor in one or the other direction comprising two circuits, each having a rela-y switch for connecting the motor to a source of current, means for operating one or the other relay switches, the selection being determined in accordance with the existence of certain predetermined pressure conditions in a combustion chamber. r r

3. In a device of the character described means for varying the pressure in a combustion chamber and control mechanism comprising a reversible motor, two field circuits for said motor, each of said circuits being normally opened, a relay for closing each of said circuits, each of said relays being connected in independent normally opened circuits, and means for selectively closing one or the other of said relay circuits according to pressure conditions in a combustion chamer. ,4.In a device of the character described. means for varying the pressure in a combustion chamber and control mechanism comprising areversible motor, two field circuits for said motor, each of said circuits being normally opened, a relay for closing each of said'circuits, each of said relays being connected in independent normally opened circuits, and means for 'selectively closing one "or-the other of said relay circuits according to pressure conditions in a combustion chamber, and switch means for cutting out said rela s and a manualswitch for selectively closing one or the 'other'of said two field circuits.

normallyopened, a relay for closing each of 120 said circuits, each of said relays being con 5. In a device of thecharacter described nected in independent normally 0 ened circuits, and a double acting switch or blosing one of said relay circuits when the pressure in a combustion chamberreaches a certain predetermined maximum, and for connecting the'other of said relay circuits when the pressure in saidcombustion chamber reaches a certain predetermined minimum.'.

6. In a'device of the character described means for varyingthe p'ressurein a combustion chamber and control mechanism comprising a reversible motor, tWo field circuits for said motor, each of said circuits being normally opened, a relay f r closing each of said circuits, each of said elays being connected in independent normally opened circuits, and means for selectively closing one or the other of said relay circuits according to pressure conditions in a combustion chamher, said means comprising a pair of spaced, fixed terminals and a movable terminal carried by a pressure responsive element, and normally out of contact with said pair of spaced terminals, but adapted to contact one or the other of said spaced terminals upon predetermined movement in either direction. 7. In a device of the character described means for varying the pressure 111 a combustion chamber and I control mechanism comprising a reversible motor, two field circuits for said motor, each of said circuits being normally opened, a relay for closing each of said circuits, each of said relays be ing connected in independent normally opened circuits, and means for selectively closing one, or the other of said relay circuits according to pressure conditions in a combustion chamber, each of said two field circuits having a normally closed limit switch adapted to be opened by said motor When in operation after a predetermined number of revolutions thereof.

Signed at Duluth, Minnesota, this 24th day of September, 1926.

FRED H. LINLEY. 

